De locht



L. De LOGHT'.

Microphone.

, No. 224,400,; Patenfed Feb. 10, I880.

; UNITED STATES PATENT OFFICE. 1 I

' LEON DE LooHT, F IlIEGE, BELGIUM.

MICROPHONE.

SPECIFICATION forming part of Letters Patent No. 224,400, dated February 10, 1880.

Application filed October Q, 1879.

To all whom it may concern: Be it known that I, LEON DE L OCH'L, of the city of Liege, in. the Kingdom of Belgium,

.is a specification.

The object of my invention is to provide a microphone which maybe introduced into the circuit of a battery containing a receiving telephone, or in the primary circuit of an induction -coil connected with the battery, the secondary circuit of the coil containing the telephone, for the purpose of receiving sound-impulses from a single direction and difi'using them in many directions simultaneously, or receiving the impulses from many directions and transmitting their combined effect in one direction. 7

My invention consists in the combination, with a vertically-arranged board or plate hav ing an extended surface, hinged at one end to a support, so as to admit of its free oscillation,

and provided at or near the other end with apiece of carbon, graphite, or an ymaterial having a low degree of conductivity, of a stop for limiting the movement of the board in one direction, and a stop consisting of carbon, graph.- ite, or similar material, for impinging on the first-said carbon and limiting the movement of the board in the other direction. To render it more sensitive, the said board or plate may be supported by springs acting uponone or both of its sides, and the carbon or graphite stops are preferably secured to springs which admit of their yielding under the pressure exerted by the board or plate upon them.

In the accompanying drawings, Figure 1 represents an edge view of a microphone embodyin g my improvements. a face view thereof; and Fig. 3 represents a view of a board or plate provided with a support of modified form.

Similar letters of reference designate corresponding parts in all the figures.

A designates a thin but stifl' board or plate of wood or other suitable material. (Here represented as of rectangular form.) This board or plate is intended to be hinged at one end, so as to admit of its oscillating freely slightly on each side of a vertical plane. As here represented, the board or plate is shown as hav- Fig. 2 represents,

ing secured to it at the lower end a metal plate or piece, A, having at eachend lugs a, furnished with conical holes or recesses.

B designates supports secured to a base or board, 0, and receiving screwsD, having conical points, which enter the conical holes in the lugs a and permit the oscillation of the board A with little friction.

- At or near the endof the board plateA,

opposite'to' the axis, is a prism, E, of carbon, graphite, or any other material which is a poor conductor of electricity, secured to the board or plate by metal clips I).

F designates a small contact-piece of carbon, graphite, or other suitable material, so arranged as to stop the oscillation of the board or plate when the piece of carbon E impinges against it. The piece F is preferably secured to the end of a spring, G, secured at one end to a support, H, extending from the base-piece G, and at about the middle of its length is a screw, 0, for regulating the tension of the g I spring Gr. I

The movement of the board or plate A is preferably limited in the opposite direction by a spring, I, secured to the base-piece O,

and carrying a screw, J, by which its tension,

may be regulated. A screw, J, forms an adjustable stop for limiting positively the movement of the board or plate A. Instead of being hinged at one edge, the board or plate A may be attached to a rod, K, extending from an oscillating axis, L, as shown clearly in Fig. 3.

The sensibility of this microphone for the transmission of feeble sounds may be increased by placing an acoustic trumpet in front of the board or plate A.

-In the operation of the instrument the cur-- to bear on the prism E, and in such case the current would enter through one contact-piece, pass through the prism E, and pass out through the other.

For arrangement in the same voltaic circuit,

or in several circuits connected with one or more telephonic lines, a number of the boards or plates A, placed side by side upon the same base, may be employed. The said boards would then receive synchronously the impulses of sound transmitted in such manner as to diffuse it in many directions simultaneously, or to increase it and render it more distinct in a receiving apparatus.

I am aware that it is old to employ a spring forming and carrying one electrode of the circuit of a telephone and constantly pressing against the other electrode and diaphragm to maintain the required initial pressure between the electrodes, and do not therefore claim this, broadly, as my invention.

What I claim as my invention, and desire to secure by Letters Patent, is

1. The combination, with a vertically-arranged board or plate having an extended surface, hinged at one end to a support, so as toadmit of its free oscillation, and provided at or near the other end with a piece of carbon, graphite, or any material having a low degree of conductivity, of a stop for limiting the movement of the board in one direction, and a stop consisting of carbon, graphite, or similar material, for impinging on the firstsaid carbon and limiting the movement of the board in the opposite direction, substantially as specified.

2. The combination, with the board or plate A, hinged at one end and provided at or near the other end with a prism, E, of carbon or other material, of a spring, I, for limiting the movement of the plate in one direction, and the spring carbon stops F G, for limiting its movement in the opposite direction, substantially as specified.

3. The combination, with the board or plate A, hinged at one end and provided at or near the other end with the prism E of carbon or other material, of the spring I, provided with an adjusting-screw, J, and the spring carbon stop F G, provided with an adjusting-screw, a, substantially as specified.

LEON DE LOOHT.

Witnesses:

JOSEPH ATTERBURY, GEo. O. TANNER. 

